Restore the Fresnel term in the BRDF.

Was uncommented in 65fd37c, mostly likely by mistake since its important.

Also made a few corrections of specular -> specular_blob_intensity (gles2).

1 files changed, 21 insertions, 20 deletions

diff --git a/drivers/gles3/shaders/scene.glsl b/drivers/gles3/shaders/scene.glsl
index bcaf4a57a8..a94558a58a 100644
--- a/drivers/gles3/shaders/scene.glsl
+++ b/drivers/gles3/shaders/scene.glsl
@@ -920,13 +920,14 @@ float GTR1(float NdotH, float a) {
 	return (a2 - 1.0) / (M_PI * log(a2) * t);
 }
 
-vec3 metallic_to_specular_color(float metallic, float specular, vec3 albedo) {
-	float dielectric = (0.034 * 2.0) * specular;
-	// energy conservation
-	return mix(vec3(dielectric), albedo, metallic); // TODO: reference?
+vec3 F0(float metallic, float specular, vec3 albedo) {
+	float dielectric = 0.16 * specular * specular;
+	// use albedo * metallic as colored specular reflectance at 0 angle for metallic materials;
+	// see https://google.github.io/filament/Filament.md.html
+	return mix(vec3(dielectric), albedo, vec3(metallic));
 }
 
-void light_compute(vec3 N, vec3 L, vec3 V, vec3 B, vec3 T, vec3 light_color, vec3 attenuation, vec3 diffuse_color, vec3 transmission, float specular_blob_intensity, float roughness, float metallic, float rim, float rim_tint, float clearcoat, float clearcoat_gloss, float anisotropy, inout vec3 diffuse_light, inout vec3 specular_light) {
+void light_compute(vec3 N, vec3 L, vec3 V, vec3 B, vec3 T, vec3 light_color, vec3 attenuation, vec3 diffuse_color, vec3 transmission, float specular_blob_intensity, float roughness, float metallic, float specular, float rim, float rim_tint, float clearcoat, float clearcoat_gloss, float anisotropy, inout vec3 diffuse_light, inout vec3 specular_light) {
 
 #if defined(USE_LIGHT_SHADER_CODE)
 	// light is written by the light shader
@@ -1085,11 +1086,11 @@ LIGHT_SHADER_CODE
 		float G = G_GGX_2cos(cNdotL, alpha) * G_GGX_2cos(cNdotV, alpha);
 #endif
 		// F
-		//float F0 = 1.0;
-		//float cLdotH5 = SchlickFresnel(cLdotH);
-		//float F = mix(cLdotH5, 1.0, F0);
+		vec3 f0 = F0(metallic, specular, diffuse_color);
+		float cLdotH5 = SchlickFresnel(cLdotH);
+		vec3 F = mix(vec3(cLdotH5), vec3(1.0), f0);
 
-		float specular_brdf_NL = cNdotL * D /* F */ * G;
+		vec3 specular_brdf_NL = cNdotL * D * F * G;
 
 		specular_light += specular_brdf_NL * light_color * specular_blob_intensity * attenuation;
 #endif
@@ -1191,7 +1192,7 @@ vec3 light_transmittance(float translucency,vec3 light_vec, vec3 normal, vec3 po
 }
 #endif
 
-void light_process_omni(int idx, vec3 vertex, vec3 eye_vec, vec3 normal, vec3 binormal, vec3 tangent, vec3 albedo, vec3 transmission, float roughness, float metallic, float rim, float rim_tint, float clearcoat, float clearcoat_gloss, float anisotropy, float p_blob_intensity, inout vec3 diffuse_light, inout vec3 specular_light) {
+void light_process_omni(int idx, vec3 vertex, vec3 eye_vec, vec3 normal, vec3 binormal, vec3 tangent, vec3 albedo, vec3 transmission, float roughness, float metallic, float specular, float rim, float rim_tint, float clearcoat, float clearcoat_gloss, float anisotropy, float p_blob_intensity, inout vec3 diffuse_light, inout vec3 specular_light) {
 
 	vec3 light_rel_vec = omni_lights[idx].light_pos_inv_radius.xyz - vertex;
 	float light_length = length(light_rel_vec);
@@ -1245,10 +1246,10 @@ void light_process_omni(int idx, vec3 vertex, vec3 eye_vec, vec3 normal, vec3 bi
 		light_attenuation *= mix(omni_lights[idx].shadow_color_contact.rgb, vec3(1.0), shadow);
 	}
 #endif //SHADOWS_DISABLED
-	light_compute(normal, normalize(light_rel_vec), eye_vec, binormal, tangent, omni_lights[idx].light_color_energy.rgb, light_attenuation, albedo, transmission, omni_lights[idx].light_params.z * p_blob_intensity, roughness, metallic, rim * omni_attenuation, rim_tint, clearcoat, clearcoat_gloss, anisotropy, diffuse_light, specular_light);
+	light_compute(normal, normalize(light_rel_vec), eye_vec, binormal, tangent, omni_lights[idx].light_color_energy.rgb, light_attenuation, albedo, transmission, omni_lights[idx].light_params.z * p_blob_intensity, roughness, metallic, specular, rim * omni_attenuation, rim_tint, clearcoat, clearcoat_gloss, anisotropy, diffuse_light, specular_light);
 }
 
-void light_process_spot(int idx, vec3 vertex, vec3 eye_vec, vec3 normal, vec3 binormal, vec3 tangent, vec3 albedo, vec3 transmission, float roughness, float metallic, float rim, float rim_tint, float clearcoat, float clearcoat_gloss, float anisotropy, float p_blob_intensity, inout vec3 diffuse_light, inout vec3 specular_light) {
+void light_process_spot(int idx, vec3 vertex, vec3 eye_vec, vec3 normal, vec3 binormal, vec3 tangent, vec3 albedo, vec3 transmission, float roughness, float metallic, float specular, float rim, float rim_tint, float clearcoat, float clearcoat_gloss, float anisotropy, float p_blob_intensity, inout vec3 diffuse_light, inout vec3 specular_light) {
 
 	vec3 light_rel_vec = spot_lights[idx].light_pos_inv_radius.xyz - vertex;
 	float light_length = length(light_rel_vec);
@@ -1280,7 +1281,7 @@ void light_process_spot(int idx, vec3 vertex, vec3 eye_vec, vec3 normal, vec3 bi
 	}
 #endif //SHADOWS_DISABLED
 
-	light_compute(normal, normalize(light_rel_vec), eye_vec, binormal, tangent, spot_lights[idx].light_color_energy.rgb, light_attenuation, albedo, transmission, spot_lights[idx].light_params.z * p_blob_intensity, roughness, metallic, rim * spot_attenuation, rim_tint, clearcoat, clearcoat_gloss, anisotropy, diffuse_light, specular_light);
+	light_compute(normal, normalize(light_rel_vec), eye_vec, binormal, tangent, spot_lights[idx].light_color_energy.rgb, light_attenuation, albedo, transmission, spot_lights[idx].light_params.z * p_blob_intensity, roughness, metallic, specular, rim * spot_attenuation, rim_tint, clearcoat, clearcoat_gloss, anisotropy, diffuse_light, specular_light);
 }
 
 void reflection_process(int idx, vec3 vertex, vec3 normal, vec3 binormal, vec3 tangent, float roughness, float anisotropy, vec3 ambient, vec3 skybox, inout highp vec4 reflection_accum, inout highp vec4 ambient_accum) {
@@ -1895,7 +1896,7 @@ FRAGMENT_SHADER_CODE
 	specular_light *= mix(vec3(1.0), light_attenuation, specular_light_interp.a);
 
 #else
-	light_compute(normal, -light_direction_attenuation.xyz, eye_vec, binormal, tangent, light_color_energy.rgb, light_attenuation, albedo, transmission, light_params.z * specular_blob_intensity, roughness, metallic, rim, rim_tint, clearcoat, clearcoat_gloss, anisotropy, diffuse_light, specular_light);
+	light_compute(normal, -light_direction_attenuation.xyz, eye_vec, binormal, tangent, light_color_energy.rgb, light_attenuation, albedo, transmission, light_params.z * specular_blob_intensity, roughness, metallic, specular, rim, rim_tint, clearcoat, clearcoat_gloss, anisotropy, diffuse_light, specular_light);
 #endif
 
 #endif //#USE_LIGHT_DIRECTIONAL
@@ -1969,11 +1970,11 @@ FRAGMENT_SHADER_CODE
 #else
 
 	for (int i = 0; i < omni_light_count; i++) {
-		light_process_omni(omni_light_indices[i], vertex, eye_vec, normal, binormal, tangent, albedo, transmission, roughness, metallic, rim, rim_tint, clearcoat, clearcoat_gloss, anisotropy, specular_blob_intensity, diffuse_light, specular_light);
+		light_process_omni(omni_light_indices[i], vertex, eye_vec, normal, binormal, tangent, albedo, transmission, roughness, metallic, specular, rim, rim_tint, clearcoat, clearcoat_gloss, anisotropy, specular_blob_intensity, diffuse_light, specular_light);
 	}
 
 	for (int i = 0; i < spot_light_count; i++) {
-		light_process_spot(spot_light_indices[i], vertex, eye_vec, normal, binormal, tangent, albedo, transmission, roughness, metallic, rim, rim_tint, clearcoat, clearcoat_gloss, anisotropy, specular_blob_intensity, diffuse_light, specular_light);
+		light_process_spot(spot_light_indices[i], vertex, eye_vec, normal, binormal, tangent, albedo, transmission, roughness, metallic, specular, rim, rim_tint, clearcoat, clearcoat_gloss, anisotropy, specular_blob_intensity, diffuse_light, specular_light);
 	}
 
 #endif //USE_VERTEX_LIGHTING
@@ -1994,7 +1995,7 @@ FRAGMENT_SHADER_CODE
 	diffuse_light *= ao_light_affect;
 #endif
 
-	//energy conservation
+	// base color remapping
 	diffuse_light *= 1.0 - metallic; // TODO: avoid all diffuse and ambient light calculations when metallic == 1 up to this point
 	ambient_light *= 1.0 - metallic;
 
@@ -2011,10 +2012,10 @@ FRAGMENT_SHADER_CODE
 		vec4 r = roughness * c0 + c1;
 		float ndotv = clamp(dot(normal, eye_vec), 0.0, 1.0);
 		float a004 = min(r.x * r.x, exp2(-9.28 * ndotv)) * r.x + r.y;
-		vec2 AB = vec2(-1.04, 1.04) * a004 + r.zw;
+		vec2 env = vec2(-1.04, 1.04) * a004 + r.zw;
 
-		vec3 specular_color = metallic_to_specular_color(metallic, specular, albedo);
-		specular_light *= AB.x * specular_color + AB.y;
+		vec3 f0 = F0(metallic, specular, albedo);
+		specular_light *= env.x * f0 + env.y;
 #endif
 	}